Whenever there is a mass shooting in the United States, it doesn't take long before pundits suggests violent video games might be to blame.
But a new report from the American Psychological Association (APA) found there is insufficient research to support that link. It found that there is evidence showing the games increase aggression but not enough to demonstrate that playing the games lead to criminal behavior or delinquency.
"Scientists have investigated the use of violent video games for more than two decades but to date, there is very limited research addressing whether violent video games cause people to commit acts of criminal violence," said Mark Appelbaum, the task force chair. "However, the link between violence in video games and increased aggression in players is one of the most studied and best established in the field."
In reviewing more than 150 research papers, the task force found a consistent relationship between the games and an increase in "aggressive behavior" as well as a decrease in "prosocial behavior, empathy, and sensitivity to aggression" and that this behavior continued for some time.
But the task force also found that the video games alone can't explain this aggression. Rather, it concluded that the "accumulation of risk factors," such as antisocial behavior, depression, trouble at home, delinquency or academic problems, also played a role.
"The research reviewed here demonstrates that violent video game use is one such risk factor," the report concluded.
The findings are unlikely to put to rest the concerns about violent video games, especially given that over 90 percent of children play video games, with 85 percent of those games containing some violence. The games came under fire in 2012 after Adam Lanza gunned down 20 children and six teachers Sandy Hook Elementary School in Connecticut. It later turned out that he was obsessed with violent video games, prompting calls from some members of Congress for restrictions on them.
Ohio State University's Brad J. Bushman, who has done extensive work on violent media including games and aggression, said he disagreed with the APA conclusion that there is no link between violent video games and violent behavior, although he acknowledged it is difficult to prove a link in an experimental setting.
"One can never know for sure whether playing violent video games causes violent criminal behavior, because it is unethical for researchers to allow participants to engage in violent criminal behavior in their laboratory experiments," Bushman told CBS News. "However, there certainly is a link between playing violent video games and violent criminal behavior, although it is not as strong as the link between playing violent video games and less serious aggressive behavior."
In one experiment in which he took part, adolescent boys were given the opportunity to blast an ostensible opponent with loud noise through headphones after being randomly assigned to play a violent or nonviolent video game. The results showed that boys who played a violent game and strongly identified with the violent game character selected noise levels loud enough to cause permanent hearing damage to their partner.
But other studies have found no link, including one from the University of Missouri in April that found violent video games did not cause gamers with Autism Spectrum Disorder - something Lanza is believed to have suffered - to act violently. Another 2013 study found that violent video games such as "Mortal Kombat," "Halo," and "Grand Theft Auto" did not trigger violence in teenagers with symptoms of depression or attentions deficit disorder.
The Entertainment Software Association, which represents the U.S. video game industry, criticized the APA study, noting that youth violence has declined to a 40-year low during the "video game epoch."
"Considering the APA's long-standing bias against and attacks on video games, this slanted report is not surprising," the group said in a statement. "Numerous medical professionals, researchers, and courts all debunk the fundamental thesis of their argument. In tearing down similar faulty research, the U.S. Supreme Court specifically ruled that 'psychological studies purporting to show a connection between exposure to violent video games and harmful effects on children do not prove that such exposure causes minors to act aggressively.' We could not state it better."
The APA task force acknowledged that more research is needed on the issue, including studies that looked at the impact of violent video games on gamers younger than 10, potential gender differences in the response of gamers as well as the effects on different ethnic groups.
But even with the limited evidence of criminal behavior, the APA is calling on the gaming industry to design video games that include increased parental control over the amount of violence the games contain.
The APA's Council of Representatives, earlier this month, also adopted a resolution encouraging the Entertainment Software Rating Board to refine its video game rating system "to reflect the levels and characteristics of violence in games, in addition to the current global ratings" and for developers to design games that are appropriate to users' age and psychological development.